1. Field of the Invention
The present invention relates to a terminal located on a network in which an improvement can be made in the communication efficiency of the network interconnected to a plurality of computers performing processing, such as information retrieval. The invention also relates to an information recording medium readable in the above type of terminal.
2. Description of the Related Art
As an increasing development of a computer network, a plurality of computers can be interconnected to a network shared by the users, and accordingly, it becomes possible to gain easy access to the information stored in the interconnected computers from a specific terminal. Various types of information are stored in the computers located on the network depending on the purposes and uses, and the user is able to access a targeted item of information according to a user interface in the form of a hierarchical tree structure which has been stored in the computer, so that the information can be retrieved.
An explanation will now be given with reference to FIG. 4 of an example of known information storage systems using a hierarchical tree-structured interface.
(1) Construction
In this example of a known art, an information storage system 103 is used to provide information concerning hobbies and business. A user 101 operates his/her terminal 102. This terminal 102 is connected to communication means 106, which is generally referred to as "a network". The network 106 achieves information communications between a plurality of computers interconnected onto the network 106 according to a specific procedure as if the computers are directly connected to each other.
The information storage system 103 is connected to the same network 106, and thus, the terminal 102 serves as a terminal of the system 103. Namely, the user 101 is able to operate the system 103 through the terminal 102. The storage system 103 is constructed of a computer controller 104 and a storage unit 105.
The storage unit 105 can store various types of information, and in this example, finally stores information about travelling, such as local maps, entertainments, hotels, etc. (hereinafter referred to as "the final information"). The contents of the storage unit 105 include not only the final information but also the attribute of the information as key information. For example, the key information 107, 108 and 109 effectively used for gaining access to the travel information, such as "New York", includes "hobby guide" 107a, "travel guide" 108b, "U.S.A." 109a, etc., respectively.
The computer controller 104 functions to (1) logically connect the storage unit 105 to the network 106, and (2) fetch the final information (the latest information 110 about, for example, "New York") or the key information 107, 108 and 109 so as to send the fetched information to the terminal 102.
(2) Operation
The operation of the storage system 103 constructed as described above will now be described in the case where the user would like to obtain the final information 110 concerning "New York" by way of example.
When the user specifies the information storage system 103, the user's terminal 102 can designate the system 103 through the network 106. Accordingly, the terminal 102 is apparently connected to the information storage system 103 on a one-for-one basis. In practice, however, the storage system 103 merely allocates the processing time to the individual users in a time-sharing manner to enable a plurality of users' terminals to access the system 103 at the same time.
Then, for guiding the information to be retrieved, the computer controller 104 of the storage system 103 fetches the items of the key information 107 located in a first level of the hierarchical tree structure stored in the storage unit 105 and outputs the information to the user's terminal 102 that the items "business guide" 107b and "hobby guide" 107a are available as the key information 107.
The terminal 102 receives the above information sent from the computer controller 104 and displays it on the terminal 102. The user 101 who would like to obtain the final information "New York" selects and specifies the "hobby guide" 107a from the key information. This is transmitted to the computer controller 104 via the terminal 102 and the network 106. Subsequently, the controller 104 fetches the items of the key information 108 positioned in a second level of the hierarchical tree structure stored in the storage unit 105 and sends the information to the user's terminal 102 that the items "music guide" 108a, "travel guide" 108b and "literature guide" 108c are available as the key information 108.
In a manner similar to the procedure described above, the user 101 selects the item "travel guide" 108b so as to cause the computer controller 104 to send the information to the terminal 102 that information about countries as travelling destinations, such as "China", "Japan", etc., are available as the key information 108 located in a third level of the tree structure stored in the storage unit 105. The user 101 is thus able to finally access the final information 110 "New York".
However, the information storage system of the above known type encounters the following problems in order to let the user 101 to access the final information by operating the terminal 102.
(1) It is necessary to thoroughly search the tree structure in the information storage system 103. More specifically, the computer used as the information storage system 103 is required to monitor, according to the related information in the form of the key information 107 through 109, in which level of the tree structure the user 101 currently connected to the system 103 refers to and which information item the user 101 has selected, thereby disadvantageously consuming computation resources.
(2) In order to display the key information 107 through 109 onto the terminal 102, the information storage system 103 is required to send onto the network 106 the key information 107 through 109 halfway through the searching of the tree structure in the storage system 103. This operation consumes network resources.
(3) Further, the tree structure of the storage unit 105 is variable, since it is constantly managed by the operator assigned to each information storage system 103. More specifically, in the aforesaid example, the item "literature guide" 108c is newly added to the items "music guide" 108a and "travel guide" 108b branched from the hobby guide 107a of the key information 108. The user 101 who is not skilled in this type of operation may be confused by this change of displaying the guide.